How do you get sweat stains out of a hat?

Apply dish soap or a baking soda paste directly to the sweatband stain. Let sit 15-30 minutes, then scrub gently and rinse.

Can you wash a cap in the dishwasher?

Despite the popular advice, dishwashers use heat and harsh detergent that damage caps. Hand washing is safer and more effective.

Place it on a cap form, upside-down coffee can, or balled-up towel. Air dry at room temperature. Never use a dryer.

Every 1-2 weeks during heavy use, or when you notice staining or odor. Spot clean between full washes.

Clothing & Footwear

Your baseball cap deserve proper care to stay looking their best. Follow these steps to clean them safely without causing damage.

1
Check the brim material
Modern caps have plastic brims (safe to hand wash). Older or vintage caps may have cardboard brims that disintegrate in water -- spot clean those only.
2
Pre-treat sweat stains
Apply dish soap directly to the sweatband and any visible stain. Let it sit for 15-20 minutes to break down oils and salt.
3
Hand wash in warm soapy water
Fill a basin with warm water and dish soap. Submerge the cap and gently scrub with a soft brush, focusing on the sweatband and stained areas.
4
Rinse thoroughly
Rinse under cool running water until all soap is removed. Squeeze gently -- do not wring or twist the cap.
5
Shape and air dry
Place the cap over a small bowl, balled-up towel, or cap form to maintain the dome shape. Air dry completely away from direct heat.

TIPNever wash a baseball cap in the dishwasher -- the heat and detergent are too harsh and cause shrinking and fading.
TIPFor persistent sweat stains, make a paste of baking soda and water, apply to the stain, let sit 1 hour, then wash.
TIPSpray new caps with fabric protector before wearing to prevent sweat stains from penetrating the fabric.

XMachine washing or drying caps, which crushes the brim, shrinks the crown, and destroys the shape.
XUsing bleach on colored caps, which causes uneven fading and weakens the fabric structure.
XDrying caps flat or crumpled, which causes the brim to warp and the crown to lose its shape permanently.

Not recommended. The agitation, heat, and spinning destroy the shape. Hand washing gives the best results.